Credit-Based Link Management for Source Synchronous ICs
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Solution Overview
Problem
In complex integrated circuits, managing source synchronous communications links with multiple virtual channels is challenging due to the need for efficient priority-based arbitration and credit management to optimize resource utilization and power conservation.
Innovation Solution
A credit-based system is implemented, where functional circuit blocks use credit management circuitry to convey credits and arbitrate requests based on transaction classes, ensuring higher priority transactions are executed and credits are maintained for efficient re-establishment of links, thereby optimizing link management and power conservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If source synchronous communication links with multiple virtual channels are implemented, then transaction priority handling and resource utilization are improved, but link management complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting credit values based on transaction priorities and link states. The credit management circuitry modifies credit parameters to control link activation/deactivation, thereby managing complexity through parameter control rather than structural complexity. This allows the system to handle multiple virtual channels efficiently while keeping management straightforward.
2Reliability
If credits are managed to ensure minimum numbers for re-establishment, then link re-establishment reliability is improved, but credit management overhead increases
Solution Approach 1:
The patent implements preliminary action by pre-establishing minimum credit thresholds before link deactivation occurs. The credit management circuitry ensures that sufficient credits are accumulated in advance to guarantee successful re-establishment of communication links. This proactive approach improves reliability while simplifying management by setting predetermined credit levels rather than dynamically calculating them during link failures.
3Use of energy by moving object
If links are deactivated when not in use to conserve power, then energy consumption is reduced, but link reactivation time increases
Solution Approach 1:
The patent applies preliminary action by maintaining minimum credit reserves before link deactivation. This ensures that when links need to be reactivated, the necessary credits are already available, eliminating delays associated with credit accumulation. The system can quickly reactivate links by simply restoring the clock signal without waiting for credit generation, thus reducing reactivation time while still achieving power savings during idle periods.
Data Source
AI summary
A system and method for communication link management in a credit-based system is disclosed. In one embodiment, a system includes first and second functional circuit blocks implemented on an integrated circuit and being able to communicate with one another through establishment of source synchronous links. The first functional circuit block includes a write queue for storing data and information regarding write requests sent from the second functional circuit block. The write queue includes credit management circuitry arranged to convey one or more credits to the second functional circuit block responsive to receiving one or more write requests therefrom. Responsive to receiving the one or more credits and in the absence of any pending additional requests, the second functional circuit block may deactivate a link with the first functional circuit block.